Download Comparing Longitudinal and Cross-Sectional Data: Exam Questions and more Exams Business Statistics in PDF only on Docsity!
22S:008 Exam 1, Part I, Feb. 19, 1999 Name:_______________________________
Please circle one. Section: 11:30, 12:30 or 2:
Please enter all of your answers on these exam pages. There are 17 questions on this part. A Defective Question Report is handed out separately.
- Which of the following data sets is longitudinal and which is cross-sectional?
a) (1 pt.) The pulse rates of patients getting their physicals at Mercy Hospital on February 12, 1999. Cross-sectional or longitudinal? b) (1 pt.) Weekly salary for Jon Dough at McDonalds from June 1995 through January 1999. Cross-sectional or longitudinal? c) (1 pt.) The ages of the women in this class today. Cross-sectional or longitudinal?
- (1 pt.) Designed experiments are active studies in which randomization is not used.
A) True B) False
- (1 pt.) A company wants to get feedback from its workers via a questionnaire. The company asks for volunteers (anyone interested) to fill out the questionnaire. The results are then compiled and studied. This is an example of a probability survey. A) True B) False
- (1 pt.) The Pareto Diagram is a basic tool for visually separating the “vital few from the trivial many.”
A) True B) False
- (4 pts.) A group is composed of 100 men and 80 women. The average (mean) weight of the men is 170 pounds and the average weight of the women is 120 pounds. What is the average (mean) weight of all 180 people? Show your work.
- (3 pts.) The average score on an exam was 78. About 68% of the scores were between 76 and 80. If you scored 84, which of the following is the most reasonable approximation to your standardized score? You may assume that the distribution of scores is mound-shaped. Show your work. A) 1 B) 2 C) 3 D) 4 E) 5
- (1 pt.) Consider the following stem-and-leaf plot.
Stem-and-leaf N = 25 Leaf Unit = 1. 0 3 0 59 1 1 1 5 2 2 2 557789 3 011223334 3 5689
What is the median of the distribution? median = ______
- (4 pts.) What is the standard deviation for the data in the table? Show your work in the table.
standard deviation = _________
- Two dotplots are shown at the right. a) (3 pts.) Which of the two has the larger standard deviation? Explain your answer.
b) (1 pt.) Which of the two has the larger range? Explain your answer.
Data y − y (^) ( y − y )^2
10
20
15
103.5 104.5 105.5 106.5 107.5 108.5 109.
Dataset
Dataset
- (4 pts.) A recent statistics book reported the following study:
Does Use of Marijuana During Pregnancy Affect Birth Weight? During 1985, approximately 31% of American women in their late teens and early 20s reported that they had used marijuana within the previous year. These are the prime reproductive years for women, and researchers were concerned about the possible effects of marijuana use during pregnancy on fetal growth and development. In the New England Journal of Medicine , Zuckerman et al. presented the results of a large- scale study of mothers, recruited over a three-year period from a general prenatal clinic. Among other findings, the researchers reported that the mean birth weight of infants born to 895 mothers who did not use marijuana during pregnancy was 3260g, with a standard deviation of 616g. The mean birth weight of infants born to 202 mothers who did use marijuana during pregnancy was 2980g, with a standard deviation of 662g.
Assume the birth weight distributions are roughly mound-shaped. Compare the birth weight distributions of mothers who did use marijuana during pregnancy with those who did not. Sketch their density histograms using the same scale on the data axis. Be sure to label the data axis carefully. You need not put a scale on the vertical axis. (You may draw smooth curves rather than steps.)
- (3 pts.) A large company two divisions. Division A has 1000 employees and Division B has 10, employees. The CEO wants to compare the gender distributions in the two divisions. What display would be best for this comparison? Explain your choice.
- (4 pts.) A set of 290 accounts in a Canadian branch of your company has a mean of $1000 and a standard deviation of $50. These are given in Canadian dollars. One Canadian dollar is worth only 0.80 US dollars. What would the mean and standard deviation of the 290 accounts be in US dollars? Show your work.
In US dollars: mean = __________________ standard deviation = __________________
- The graph at the right shows quarterly earnings for the Dayton-Hudson company over several years. Dayton- Hudson owns retail department stores including Target. (There are four values per year. The fourth quarter includes Christmas.) a) (2 pts.) Describe the longitudinal variation using terms like random, meandering, or seasonal.
b) (3 pts.) The graph at the right shows the percentage changes for the Dayton-Hudson quarterly earnings shown in the previous question. Describe this sequence of percentage changes using terms like random, meandering, or seasonal. Describe any unusual features of the graph.
- (4 pts.) Find the correlation coefficient for the data pairs in the table below. Show your work in the table and label the columns appropriately. The standard deviation of X is 1 and of Y is 2. You may use these standard deviations without having to calculate them. You may not need all of the columns shown.
X Y
3-31-75 12-26-77 9-22-80 6-20-
0
50
100
150
Date
Earnings
1 2 3
4 1 2^3
4 1 2
3
4
(^1 )
3
4
1 2
3
4
1 2
3
4
123
4
1 2
3
4
1
23
4
3-31-75 12-26-77 9-22-80 6-20-
100
200
300
400
500
600
700
800
Date
% Changes 2 3
4
1
2
3
4
1
2 3
4
1 2
3
4
1
2 3 4
1
2
3 4
1 2
3
4
1
2 3
4
1
(^2 )
4
Defective Question Report
Name:_____________________________________________________________________ Section:_______________________
If you believe that a test question is defective in some way, please list y our complaint here. All complaints will be considered in our interpretation of the test results.
Question number: _____ Your complaint:
Question number: _____ Your complaint:
Question number: _____ Your complaint:
